Although improvisation can be taught in a big band setting, it is not the best use of ensemble time. A small group is much better for improvisation; all that is needed is a music teacher, a few students, and a play-along recording. Even if none of the students know how to improvise, it is easy to get them started. Here, Lizotte offers tips for teaching improvisation in a combo setting.
Lizotte, Tom (2016) Improvisation in Beginning Jazz Combos. In: The Instrumentalist, Vol. 71, No. 1, pp. 36. Available at http://openmusiclibrary.org/article/456314/.